Segmented rotating band for artillery projectiles



Oct. 21, 1958 5. MICHAEL 2,

- SEGMENTED ROTATING BAND FOR ARTILLERY PROJECTILES' Filed June 2, 1955" 'INVENTOR. .Lcluis ELMiBhae].

.HZITDRNEY'S.

nitcd States Patent SEGMENTED ROTATING,BANDEQRARTILIJERY" PRomen -Es;

i This invention relates to a segmented rotating band forzart'illery p'rojectiles and "more particularly to Jthe'em- I ployment of bands of {sintered ironlbands "or'other sintered j metals-applied to the projectile intwo ,ormorelsegmentsl: V

The advantages in the use ofgildin'g metalin rotating bands are well known in view ofits plasticity andithe ease'with which 'it' flows, intothe grooves ,during its pas sage "downarilled" barrel. Regardless ofjwhether the barrel is lined, platedwithfa hardenediliner, hardened as by nitr'i'ding of not treatedat all,,the'plastic nature of the gilding metal lessens wear, and'erosion on the'lands and grooves of thebarrel.

Notwithstanding its plasticity, rotating bands' of gilding metal are not 'alwa'ys1 suitabl'eiunder certain conditions,- such as the fast loading and rapid firing inherent-in automatic rii les.,, The explanation or: thisds simple-1;, Under. comparatively slow loading'and firing,. the gildiiigunetal. has adequate; time to new info the rifling ,grooveEsIof the barrel, andsincfe' there is a little or,no resistance tothis flow band pressures do notin'creaseimmediatelyl However if the speed with which; the projectile traverses the bore..is increased, the gilding metal has insufficient time to flow into the grooveswitnthe res'ult'th'at tremendous pressures are rtedi'on;. he-biar eli ai r thereby crease material fatigue and relatively earlyfailure. of .the ba rel; I

The advantages in asinterediro'n band deriv'e'from its skeletal or porous structure which permits the metal to give or collapse into the rifiing grooves regardless of the speed with which the projectile traverses the barrel bore. For this reason band pressures are lower than, those produced by gilding metal bands, and obturation, range and accuracy for any fixed round of ammunition, and barrel life, are improved.v

It is therefore of great importance to maintain the porosity of the sintered iron band during manufacture and assembly into the completed round. Where a band is formed as a continuous ring it must be fabricated with an inner diameter a little greater than the outer diameter of the finished projectile. Thereafter the band is deformed into place to tightly engage the band seat or channel in the projectile. This procedure is satisfactory in the case of bands of gilding metal. With sintered metal bands, however, this forcing and deformation efiects a change in the skeletal structure and destroys to a large extent the porosity of the band and the advantages otherwise offered by the porosity of sintered iron or bronze. As a result the band does not lend itself as readily to engraving during firing, and destroys to a large extent the advantages to be gained by decreased pressures of bands of sintered metal.

With the present invention, it is proposed to make the band in at least two arcuate segments, each segment to curve in the direction of its length and conjointly form a ward, faces. to have a ,dovetail shapein. transverse cross section .;so,that,gthe rotating band may,be forcedzinto the undercut-portions'to efiecta tightfitand intimate engage; ment with the-channel or undercutportion to maintain; the band in itsseat under-all stresses, particularlycen-.- trifugal forces set-up bythespinning projectile. By virtue of the -fact that theband-issplit, and canbe fabricated,. to, a size closer to its-finished outer diameterwhen-seated, forcing and gconsequent deformation to; fit the. v band, into. place is: minimized, and; mostof. its original porosity; is retained. Theend result-,is -a.band which lendsitself' more easily to engraving as .it-enters. the riiling, thereby, decreasing; bandpressures, improving; obturationl of pro pellentgases, increasing muzzlewelocity, range andaccu-v racy as well as reducingjbarrel'wear. It is,,therefo re; afprimary ObjeCt.Of th;lHVentlOIlf to, provide; a. rot-ating bandt ormed,of at least,two segments toy omt b ndhaving t s, no i m pp im y. equal to the outer diameter of the band. seat of a. projectile.

I i no her; bie ttof t e. inventi n Provide projectile in; whic h the seated; rotating bands are of undeformed or substantially undeformed sintered, ironor, bronze.

Another object is, ;t0; pr;ovide;a band- 0f; atleast two segments -tqallowr fitting; of same yin; ,anannular. undercut groovq formed in; fizgPI'Qlfiiflfiwithout the necessity of unduly forcing the band imorder-to seatsamein the band at: groove.

Anothe z biect :is'to.prov de rotatina .ba d fi I ntere iIO Is AT Qi end n l -.rea vi o.e ra vy mbarrel landst diw o tere nd pr Tlie-finventionavill eebes un er od m acons er tion of the following detailed description taken inconnectiion \wittr.thezace mpanyioe drawi gitgbeing understoodzhoweventhat the in vention is-not; to be,considered as limited. by -the' specific; illustratipmpr description but that) such; illustration and es r ptio rc stitutes. Pr s.-

ferred embodiment-ofabet-i vent ons j Inthe drawiogzl i Fig. 1 is a fragmentary sectional view of a rotating band constructed in accordance with the invention and seated in an undercut band groove formed in an artillery projectile prior to seating, and illustrating the manner in which the two or more segments of the band blank fit the band seat without resort to a preliminary seating operation.

I Fig. 2 is a fragmentary'sectional view of the band of Fig. 1 after the seating operation and illustrating how the undercut portions of the groove are filled with the sintered metal forming an interlock with the projectile.

Fig. 3 is a similar View illustrating a modified band and a modified band seating groove, prior to the seating operation.

Fig. 4 is a similar view of another modification.

Fig. 5 is a similar view of yet another modification.

Fig. 6 is a side elevation illustrating two segments forming a band blank of the invention, and Fig. 7 is a fragmentary side elevation illustrating a method of interfitting the segments together at their respective ends.

In the drawings, 1 indicates generally a projectile, a rearward portion of which is illustrated in Fig. 1. An annular rotating band seating groove indicated generally by 2 is cut in the outer periphery of projectile 1 and is undercut at its rear and forward faces as at 3, to form an annular channel of dove-tail transverse section. The groove 2 is, in the form being described, shown with a cylindrical bottom 4. The numeral 5 indicates generally an annular rotating band of sintered iron or bronze and is split into at least two segments 6 and 7, as seen in Fig. 6. The width W of the segments 6- and 7 is sub- 7 A modified form of a seating groove for the rotating band a is illustrated in Fig. 3. The under surface of the band blank is of concave contour transversely of the band as at 9 and annular ribs notched at intervals along their lengths are formed in the surface 4 forfirmer anchorage in the groove upon deformation of the band. Another variation of the under surface of band 5b is illustrated in Fig. 4 as at 11, while Fig. 5 illustrates a seating groove similar to Figs. 3 and 4, but having the rotating band with a plain inner cylindrical surface as in Fig. 1. Ribs 10 should be interrupted at intervals. Alternatively ribs 10 may be replaced by a series of prongs which bite into the ring on deformation into the groove. The rotating band is applied by placing the segments 6 and 7 into the channel or groove, a slightly snug fit being provided if desired, to frictionally hold the segments in,

position, after which the band is deformed into the seated or finished position as Fig. 2, by any suitable procedure such as the use of a ring die.

The segments may be provided with interfitting dowels and bores at the respective ends thereof as indicated upon Fig. 7 at 6a, 7a to frictionally secure the segments together within the channel until fully seated.

Due to the fact that the segmented rings can be fitted directly into the grooves, they are fabricated to a diameter much nearer their final diameter than would be possible were they made in solid or continuous form. Thus they can be forced into the completed position shown upon Fig. 2 with lower radial forces and less deformation and crushing of the cellular or porous structure of the sintered metal. As a result, the completed projectile retains the advantages in the use of metal of this nature to a degree not heretofore attained and the objects previously recited are effected.

It will be noted that the completed segments 6, 7 after sintering have substantially the same inner radius of curvature as the radius of curvature of the bottom of the channel 4. It is also to be noted that the total inner circumferential extent of the segments after sintering and before assembly with the projectile is substantially equal 4 to the circumferential extent of the bottom of the channel 4.

It is to be understood that the form of the invention herewith shown and described, is to be taken as a preferred example of the same, and that various changes in the shape, size, and arrangement of parts may be resorted to, without departing from the spirit of the invention, or the scope of the subjoined claims.

The invention described herein may be manufactured and used by or for the Government for governmental purposes without the payment to me of any royalty thereon.

Having now fully disclosed the, invention, what I claim and desire to secure by Letters Patent is:

The combination with a projectile having an annular rotating band channel in its exterior cylindrical surface, both side walls of said channel being undercut, of an annular rotating band of sintered metal split into at least two equiangular arcuate segmentsps aid segments having substantially-the same inner radius of curvature as the radius of curvature of the bottom of said channel and being of substantially the same total circumferential extent as the circumferential extent of the bottom of said channel after sintering and before assembly in said channel and being fitted into said channel to form a continuous annular rotating band therein and adapted to completely fill the undercut portions of said channel when radial pressure is applied thereto.

References Cited in the file of this patent UNITEDLSTATES PATENTS OTHER REFERENCES The'Shelling Report, by Capt. B. B. Small, Antiaircraft Journal, September-October 1952 (pp. 15-20). 

